This invention relates to heat exchangers, and more particularly, to side pieces for use with heat exchangers having tubular headers.
Many heat exchangers manufactured today in which air or another gas is the cooling fluid or the fluid to be heated employ side pieces. Side pieces flank the sides of a heat exchanger and typically extend between the headers on opposite ends thereof. Tubes extending between the headers are spaced from one another and disposed between the side pieces and serpentine fins are located between adjacent ones of the tubes as well as the end most tubes and the side pieces.
The side pieces provide a measure of rigidity to the assembly of the headers, tubes and fins, particularly during whatever process is employed to bond these components together, whether soldering, brazing, welding or a combination of two or more of the above methods. They serve to allow an assembled, but unbonded core to be placed in a fixture wherein the bonding operation can take place.
Conventionally, the side pieces may be attached to the headers as by tabs that extend through an opening in a header plate or into the end of a tubular header. These side piece designs typically require fixturing that includes the capability of holding the side piece against the header during the bonding operation in addition to whatever fixturing is required to maintain the entire unassembled core in the proper configuration for bonding.
Even with such fixturing, bonding consistency and quality between the side pieces and the headers varies substantially, thereby affecting the rejection rate of heat exchangers after the bonding process. The present invention is directed to overcoming one or more of the above problems.
It is the principal object of the invention to provide a new and improved side piece for a heat exchanger. It is also an object of the invention to provide a heat exchanger having a new and improved side piece. It is an object of the invention to provide a side piece that may be bonded to a header with improved consistency and which results in a high quality bond. It is also an object of the invention to provide a side piece that can be assembled to a header prior to bonding without employing the fixturing heretofore required at this interface of the components.
An exemplary body of the invention achieves the foregoing objects in a heat exchanger having opposed, spaced, parallel tubular headers. Aligned, facing tube slots are located in the headers and elongated, flattened tubes that are spaced from one another extend between the headers and have opposite ends sealingly received in corresponding ones of the slots. Side pieces extend between the headers at corresponding ends thereof and are spaced from the tubes. Serpentine fins are disposed between the tubes and between the tubes and the side pieces and bonded thereto. The invention contemplates the improvement wherein each of the side pieces includes an elongated base terminating in two relatively stiff, spaced fingers. The space between the fingers is such as to partially surround the majority of the periphery of the corresponding header end and frictionally grasp the same. The capability of surrounding a majority of the periphery of the header end and frictionally grasping the same eliminates the need for fixturing at this location and improves the consistency and quality of the bonded joint therebetween.
In one embodiment of the invention the fingers are defined by concave recesses at each end of the base which open to the respective end of the base. Each recess has a shape conforming to the cross-sectional shape of the end of the corresponding header and is narrower at its opening to the end of the base than at a point between the opening and a remote part of the recess.
In a preferred embodiment, the base is bone-shaped.
In one embodiment, the cross-sectional shape of the headers is generally circular and the recesses have a wall with an angular extent of more than 180xc2x0.
In a highly preferred embodiment, each recess has a bottom opposite the opening and a slot is located in the base having one end opening to the recess and an opposite end in the base remote from the recess. The slot facilitates resiliency in the fingers.
Preferably, the opposite end of the slot terminates in an enlarged opening having a curved, stress relieving periphery. Preferably, the periphery of the enlarged opening is generally circular to provide stress relief.
One embodiment contemplates that the base have flanges extending along each side thereof and along its length. The flanges are directed towards a side of the base remote from the tubes.
In one embodiment, the base is wider about the recesses than at points between the recesses and the flanges have a lesser height adjacent the recesses than at the points between the recesses. This allows the side piece to be formed from a strip of material having a uniform width.
In a preferred embodiment, the recesses or fingers have diverging cam surfaces at the recess openings, allowing the fingers of the side piece to be cammed onto the headers.
Other objects and advantages will become apparent from the following specification taken in connection with the accompanying drawings.